1. Field of the Invention
The present invention relates to monitoring of environmental parameters and, more particularly, to a wireless sensor system with sensor nodes that can be deployed over a wide monitoring area.
2. Background of the Related Art
There is a great need for distributed measurements of environmental parameters in DoD sites to meet Total Maximum Daily Load (TMDL) requirements and to gauge sources and dynamics of pollution in large water bodies.
Current sensor platforms are relatively big, e.g., floats that are several feet long, or moored buoys. The sensors that are designed for use on these platforms tend to be bulky in design.
Currently used commercial sensors are based on a variety of operational principles. For example, dissolved oxygen (DO) is usually measured using a membrane covered amperometric cell that has a current output, pH is measured with a potentiometric electrode with voltage output, and turbidity is measured using an optical transducer by transmission, reflection, or backscattering methods. Conductivity is measured by contact (current through 2 or more electrodes) or contact-less (inductive) methods. Further, CO2 is rarely measured with sensors.
Many contaminants are generally measured in the laboratory using chromatography. This variety mandates the use of multiple electronic front-ends capable of handling the signal from the transducers. As a result, integration is difficult.